Love all the sci-fi, can't be bothered with the others.
Have just re-read Phlebas, Excession, Inversions, Windward, Player and Weapons as I've been on the sick for a couple of weeks. I love them all, although Phlebas and Windward probably have the greatest depth, with the former just edging the latter. I go as far as saying Phlebas is a truly great work of fiction.
This time around I got even more out of them and noted that there's an interesting progression of ideas in that there's stuff about games (Damage) and people as weapons (Horza) in Phlebas then more stuff about people as weapons (Gurgeh) in Player, etc., etc. so you can sort of map his thought processes from one to the next.
I occasionally amuse myself by trying to count the number of inversions in Inversions, there are lots.
A new Culture novel is scheduled for next year BTW.